1. Field of the Invention
The present invention relates to a nozzle for dispensing liquid or semi-liquid substances.
2. Description of the Related Art
There already exist dispenser nozzles designed to be mounted on tanks and suitable for being put under pressure.
In general, the delivery valve is situated inside the pump mechanism that serves to deliver the substance. The pump is actuated by a pushbutton forming a spray-nozzle.
Nevertheless, since the nozzle is mounted downstream from the delivery valve, there remains a volume of substance that is exposed to air between said valve and the ejection orifice of the nozzle.
In certain fields of application, and in particular with pharmaceuticals and cosmetics, this volume of substance that is not protected from the outside atmosphere can become contaminated by bacterial pollution or can dry out and thus block the ejection duct.
Under such conditions, the substance remaining in the tank becomes unusable.
To remedy that difficulty, CH-A-178923 proposes a nozzle comprising:
a thimble provided firstly with a coupling end for coupling to the tank and secondly with an ejection orifice; and PA1 a moving shutter housed inside said thimble, the shutter being constituted by a rod carrying a plug at its outer end which co-operates with the ejection orifice to form a delivery valve, and carrying a transverse wall at its inner end that leaves a passage for the substance and that co-operates with resilient return means for returning the moving shutter towards a closed position in which the plug is engaged in sealed manner in the delivery orifice. PA1 a thimble provided firstly with a coupling end for coupling to the tank and secondly with an ejection orifice; and PA1 a moving shutter housed inside said thimble, the shutter being constituted by a rod carrying a plug at its outer end which co-operates with the ejection orifice to form a delivery valve, and carrying a transverse wall at its inner end that leaves a passage for the substance and that co-operates with resilient return means for returning the moving shutter towards a closed position in which the plug is engaged in sealed manner in the delivery orifice; PA1 the nozzle being characterized in that it further comprises an admission valve constituted by a deformable peripheral lip subdividing the passage for the substance around the rod in sealed manner into an upstream compartment and a downstream compartment.
Nevertheless, since the shutter is actuated manually, the pressure difference that controls both opening and closing of the delivery valve is small (about 0.1 bars).
This means that after the shutter has been released and the delivery valve has closed, sealing is not sufficiently effective to ensure that no air is taken in.
Under such conditions, there remains a risk of the substance becoming polluted.
An object of the present invention is to solve that technical problem in satisfactory manner by improving sealing of the nozzle so that it can be used with sterile substances.